In the preparation process of carbon nanotubes, various point defects inevitably come into being in the lattice structures. The defects strongly affect the thermal transport properties of carbon nanotubes. Thermal conduction in carbon nanotube is simulated by using nonequilibrium molecular dynamics method with reactive bond order (REBO) potential. Thermal conductivities of carbon nanotubes with and without defects are calculated for comparison. An orthogonal array testing strategy is employed. In the calculation it greatly saves the experimental effort and identifies the degrees of influence of such structural factors as defect type, tube length, tube radius, etc. on thermal conductivity of tube. The effects of three types of point defects: vacancy, doping and adsorption are primarily studied, and the ambient temperature factor is also analyzed. Simulation results show that the thermal conductivity of carbon nanotubes with defects decreases significantly due to point defects compared with that of perfect carbon nanotubes. The defect type has the first greatest influence on the decrease of thermal conductivity, and hvae the second third greatest infuluences respeetively the radius and the length of carbon nanotubes. The degrees of influence of the above types of point defect are in the order of vacancydopingadsorption. Different types of point defects have different effects on tubes at different ambient temperatures.